Turimex monterrey

I'm thinking of going to Monterrey within the next few weeks. I see that Greyhound, Turimex, and Omnibus offer routes between Austin and Monterrey. Which one is the best? Is it safe to ride a bus across the Mexican border or should I just pay the extra money for a plane ticket?

Anyone every done this? I ended up buying a cheap flight to Guadalajara (through Volaris) from Austin, but return flights are more expensive, and I am just thinking of taking some time and eventually busing back to Austin. I could fly from Monterrey to AUS for a decent price (but long as it is via Detroit) but it is about 3 times more than the bus, or I figure just bus the 10 hours back instead.
How are the bus lines back? Any one in particular that is better than the others (don't mind paying a bit more)? It seems like Greyhound and Turimex are the two that I see online that I can book easily.